scholarly journals Photometric Observations of the Sun

1994 ◽  
Vol 143 ◽  
pp. 117-129
Author(s):  
Gary A. Chapman
Keyword(s):  
Time Scales ◽  
Solar Irradiance ◽  
Broad Band ◽  
Total Solar Irradiance ◽  
Early Years ◽  
Solar Variability ◽  
The Sun ◽  
Terrestrial Atmosphere ◽  
Photometric Observations ◽  
Disparate Data

Ground-based calorimetry and photometry of the Sun have been carried out for many years. Following the early years, ground-based photometry has largely replaced ground-based calorimetry, in part due to the advent of airborne and spaceborne detector systems for the broad-band measurement of the solar irradiance and the realization of the difficulty of correcting calorimetry measurements for the effects of the terrestrial atmosphere. Even from spacecraft, recent measurements of the total solar irradiance range from about 1367 to 1374 W/m2. Most of this difference can be ascribed to differences in instrumental scales, while a variation of about 1 to 2 W/m2 appears to be due to solar variability. The quiet Sun may also change, globally, over longer time scales. Using disparate data to understand solar variability will require cooperation between a number of current groups, supported by various governments, covering several zones of longitude.

Data Fusion of Total Solar Irradiance Composite Time Series Using 40 years of Satellite Measurements: First Results 

2021 ◽  
Author(s):  
Jean-Philippe Montillet ◽  
Wolfgang Finsterle ◽  
Werner Schmutz ◽  
Margit Haberreiter ◽  
Rok Sikonja
Keyword(s):  
Time Series ◽  
Data Fusion ◽  
Solar Irradiance ◽  
Total Solar Irradiance ◽  
Maunder Minimum ◽  
The Sun ◽  
Climate Reconstructions ◽  
The Earth ◽  
First Results ◽  
The Difference

<p><span>Since the late 70’s, successive satellite missions have been monitoring the sun’s activity, recording total solar irradiance observations. These measurements are important to estimate the Earth’s energy imbalance, </span><span>i.e. the difference of energy absorbed and emitted by our planet. Climate modelers need the solar forcing time series in their models in order to study the influence of the Sun on the Earth’s climate. With this amount of TSI data, solar irradiance reconstruction models  can be better validated which can also improve studies looking at past climate reconstructions (e.g., Maunder minimum). V</span><span>arious algorithms have been proposed in the last decade to merge the various TSI measurements over the 40 years of recording period. We have developed a new statistical algorithm based on data fusion.  The stochastic noise processes of the measurements are modeled via a dual kernel including white and coloured noise.  We show our first results and compare it with previous releases (PMOD,ACRIM, ... ). </span></p>

First TSI results and status report of the CLARA/NorSat-1 solar absolute radiometer

2018 ◽  
Vol 14 (A30) ◽  
pp. 358-360
Author(s):  
Benjamin Walter ◽  
Bo Andersen ◽  
Alexander Beattie ◽  
Wolfgang Finsterle ◽  
Greg Kopp ◽  
...  
Keyword(s):  
Solar Irradiance ◽  
Attitude Control ◽  
Total Solar Irradiance ◽  
Status Report ◽  
The Sun ◽  
Measurement Result ◽  
Satellite Attitude ◽  
Satellite Attitude Control ◽  
Electrical Interference ◽  
Investigation Problems

AbstractThe Compact Lightweight Absolute Radiometer (CLARA) is orbiting Earth on-board the Norwegian NorSat-1 micro-satellite since 14th of July 2017. The first light total solar irradiance (TSI) measurement result of CLARA is 1360.18 W m−2 for the so far single reliable Channel B. Channel A and C measured significantly lower (higher) TSI values and were found being sensitive to satellite pointing instabilities. These channels most likely suffer from electrical interference between satellite components and CLARA, an effect that is currently under investigation. Problems with the satellite attitude control currently inhibit stable pointing of CLARA to the Sun.

scholarly journals Changes in the Total Solar Irradiance and climatic effects

2021 ◽  
Vol 11 ◽  
pp. 40
Author(s):  
Werner K. Schmutz
Keyword(s):  
Solar Irradiance ◽  
Total Solar Irradiance ◽  
Cold Climate ◽  
Global Temperature ◽  
Ice Age ◽  
Large Temperature ◽  
List Type ◽  
The Sun ◽  
Solar Forcing ◽  
Direct Forcing

The correlation between the averaged reconstructed March temperature record for Kyoto, Japan, and the reconstructed Total Solar Irradiance (TSI) irradiance over 660 years from 1230 to 1890 gives evidence with 98% probability that the Little Ice Age with four cold periods is forced by variations of TSI. If the correlation is restricted to the period 1650–1890, with two cold periods in the 17th and 19th century and for which two independent reconstructed March temperature records are available, the probability of solar forcing increases to 99.99%. As solar irradiance variations have a global effect there has to be a global climatic solar forcing impact. However, by how much global temperature were lower during these minima and with what amplitude TSI was varying is not accurately known. The two quantities, global temperature and TSI, are linked by the energy equilibrium equation for the Earth system. The derivation of this equation with respect to a variation of the solar irradiance has two terms: A direct forcing term, which can be derived analytically and quantified accurately from the Stefan-Boltzmann law, and a second term, describing indirect influences on the surface temperature. If a small TSI variation should force a large temperature variation, then it has to be the second indirect term that strongly amplifies the effect of the direct forcing. The current knowledge is summarized by three statements:During the minima periods in the 13th, 15/16th, 17th, and 19th centuries the terrestrial climate was colder by 0.5–1.5 °C;Indirect Top-down and Bottom-up mechanisms do not amplify direct forcing by a large amount, i.e. indirect solar forcing is of the same magnitude (or smaller) as direct solar forcing;The radiative output of the Sun cannot be lower by more than 2 Wm−2 below the measured present-day TSI value during solar cycle minimum.These three statements contradict each other and it is concluded that at least one is not correct. Which one is a wrong statement is presently not known conclusively. It is argued that it is the third statement and it is speculated that over centennial time scales the Sun might vary its radiance significantly more than observed so far during the last 40 years of space TSI measurements. To produce Maunder minimum type cold climate excursions, a TSI decrease of the order of 10 Wm−2 is advocated.

Millennial solar irradiance forcing (Hallstatt’s cycle) in the terrestrial temperature variations

2020 ◽  
Author(s):  
Valentina Zharkova ◽  
Simon Shepherd ◽  
Elena Popova
Keyword(s):  
Magnetic Field ◽  
Solar Irradiance ◽  
Principal Component ◽  
Total Solar Irradiance ◽  
Maunder Minimum ◽  
The Sun ◽  
Inertial Motion ◽  
Temperature Variations ◽  
Background Magnetic Field ◽  
Baseline Temperature

<p>In this paper we explore the millennial oscillations (or Hallstatt cycle) of the baseline solar magnetic field, total solar irradiance and baseline terrestrial temperature detected from Principal Component Analysis of the observed solar background magnetic field. We confirm the existence of these oscillations with a period of 2100-2200 years with the similar oscillations detected in carbon 14C isotope abundances and with wavelet analysis of solar irradiance in the past 12 millennia indicating the presence of this  millennial period among a few others. We also test again the idea expressed in our paper Zharkova et al, 2019 that solar inertial motion (SIM) can cause these millennial variations because of a change of the distance between the Sun and Earth. In this paper we use the S-E distance derived from the current JPL ephemeris, finding that currently starting from the Maunder minimum the Sun-Earth  distance is reducing by 0.00025 au per 100 years, or by 0.0025 au per 1000 years.. We present the estimation of variations of solar irradiance caused by this variation of the S-E distance caused by solar inertial motion (SIM) demonstrating these variations to be closely comparable with the observed variations of the solar irradiance measured by the SATIRE payload. We also estimate the baseline temperature variations since Maunder Minimum caused by the increase of solar irradiance caused by the recovery from grand solar minimum and by reduction of the S-E distance caused by  SIM. These estimations show that the Sun will still continue moving towards the Earth in the next 700 years that will result in the increase of the baseline terrestrial temperature by up to 2.5◦C in 2700. These variations of solar irradiance will be over-imposed by the variations of solar activity of 11 cycles and the two grand solar minima occurring in 2020-2053 and 2370-2415 caused by the double dynamo actions inside the Sun.</p>

A reproducible solar irradiance estimation process using Recurrent Neural Network

2020 ◽  
Author(s):  
Amita Muralikrishna ◽  
Rafael Santos ◽  
Luis Eduardo Vieira
Keyword(s):  
Neural Network ◽  
Recurrent Neural Network ◽  
Solar Irradiance ◽  
Total Solar Irradiance ◽  
The Sun ◽  
Biological Processes ◽  
Rapid Variation ◽  
Future Studies ◽  
Analysis Process ◽  
Spectral Solar Irradiance

<p>The Sun have a constant action on Earth, interfering in different ways on life in our planet. The physical, chemical and biological processes that occur on Earth are directly influenced by the variation of solar irradiance, which is a function of the activity in the Sun’s different atmospheric layers and their rapid variation. Studying this relationship may require the availability of a large amount of collected data, without significant gaps that could be caused from many kinds of issues. In this work, we present a Recurrent Neural Network as an option for estimating the Total Solar Irradiance (TSI) and the Spectral Solar Irradiance (SSI) variability. Solar images collected on different wave components were preprocessed and used as the input parameters, and TSI and SSI data collected by instruments onboard of SORCE were used as reference of the results we expected to achieve. Complementary to this approach, we opted for developing a reproducible procedure, for which we chose a free programming language, in attempt to offer the same kind of results, with same accuracy, for future studies which would like to reproduce our procedure. To achieve this, reproducible notebooks will be generated with the intention of providing transparency in the data analysis process and allowing the process and the results to be validated, modified and optimized by those who would like to do it. This approach aims to obtain a good accuracy in estimating the TSI and SSI, allowing its reconstruction in gap scales and also the forecast of their values six hours ahead.</p>

scholarly journals On the Fluctuations of the Total Solar Irradiance

1993 ◽  
Vol 157 ◽  
pp. 107-107
Author(s):  
W. Schröder ◽  
H.J. Treder
Keyword(s):  
Solar Irradiance ◽  
Energy Production ◽  
Heat Budget ◽  
Total Solar Irradiance ◽  
The Sun ◽  
Solar Constant ◽  
The Earth ◽  
Major Semi Axis ◽  
Fundamental Quantity ◽  
The Mean

The fundamental quantity for the total solar irradiance is the solar constant J which is determined by the mean Sun-Earth distance and by the energy budget in the interior of the sun. The mean distance is the major semi-axis of the earth orbit and therefore a constant of celestial mechanics. The energy production and transport in the interior of the sun must be constant at least during a Helmholtz-Kelvin period. Actually, the heat budget of the sun is constant during some billion years.

Irradiance Observations of the Sun

1994 ◽  
Vol 143 ◽  
pp. 28-36 ◽  
Author(s):  
Claus Fröhlich
Keyword(s):  
Solar Activity ◽  
Time Scales ◽  
Solar Maximum ◽  
Activity Cycle ◽  
Total Solar Irradiance ◽  
The Sun ◽  
Direct Influence ◽  
Magnetic Network ◽  
Over Time

Measurements of the total solar irradiance during the last 14 years from satellites show variations over time scales from minutes to years and decades. The most important variance is in the range from days to several months and is related to the photospheric features of solar activity: decreasing the irradiance during the appearance of sunspots, and increasing it by faculae and the bright magnetic network. Long-term modulation by the 11-year activity cycle is observed conclusively with the irradiance being higher during solar maximum. The accuracy of the determined variability and its interpretation in terms of manifestations of activity related features on the photosphere is discussed. Besides the direct influence of the spots, faculae and magnetic network more profound changes in the thermal transport seem to influence the behaviour of the solar photospheric radiation on the solar cycle and longer time scales.

scholarly journals Modelling solar irradiance from ground-based photometric observations

2020 ◽  
Vol 10 ◽  
pp. 45 ◽  
Author(s):  
Theodosios Chatzistergos ◽  
Ilaria Ermolli ◽  
Fabrizio Giorgi ◽  
Natalie A. Krivova ◽  
Cosmin Constantin Puiu
Keyword(s):  
Solar Cycle ◽  
Solar Irradiance ◽  
Total Solar Irradiance ◽  
Visible Range ◽  
Solar Cycles ◽  
Term Trend ◽  
Photometric Observations ◽  
San Fernando ◽  
Long Term Trend

Total solar irradiance (TSI) has been monitored from space since 1978, i.e. for about four solar cycles. The measurements show a prominent variability in phase with the solar cycle, as well as fluctuations on timescales shorter than a few days. However, the measurements were done by multiple and usually relatively short-lived missions. The different absolute calibrations of the individual instruments and the unaccounted for instrumental trends make estimates of the possible long-term trend in the TSI highly uncertain. Furthermore, both the variability and the uncertainty are strongly wavelength-dependent. While the variability in the UV irradiance is clearly in-phase with the solar cycle, the phase of the variability in the visible range has been debated. In this paper, we aim at getting an insight into the long-term trend of TSI since 1996 and the phase of the solar irradiance variations in the visible part of the spectrum. We use independent ground-based full-disc photometric observations in Ca II K and continuum from the Rome and San Fernando observatories to compute the TSI since 1996. We follow the empirical San Fernando approach based on the photometric sum index. We find a weak declining trend in the TSI of $ {-7.8}_{-0.8}^{+4.9}\times 1{0}^{-3}$ Wm−2 y−1 between the 1996 and 2008 activity minima, while between 2008 and 2019 the reconstructed TSI shows no trend to a marginally decreasing (but statistically insignificant) trend of $ {-0.1}_{-0.02}^{+0.25}\times 1{0}^{-3}$ Wm−2 y−1. The reference TSI series used for the reconstruction does not significantly affect the determined trend. The variation in the blue continuum (409.2 nm) is rather flat, while the variation in the red continuum (607.1 nm) is marginally in anti-phase, although this result is extremely sensitive to the accurate assessment of the quiet Sun level in the images. These results provide further insights into the long-term variation of the TSI. The amplitude of the variations in the visible is below the uncertainties of the processing, which prevents an assessment of the phase of the variations.

scholarly journals Total Solar Irradiance Variations: The Construction of a Composite and its Comparison with Models

1998 ◽  
Vol 185 ◽  
pp. 89-102 ◽  
Author(s):  
Claus Fröhlich ◽  
Judith Lean
Keyword(s):  
Time Series ◽  
Time Scales ◽  
Solar Irradiance ◽  
Total Solar Irradiance

Measurements of the total solar irradiance (TSI) during the last 18 years from spacecraft are reviewed. Corrections are determined for the early measurements made by the HF radiometer within the ERB experiment on NIMBUS7 and the factor to refer ACRIM II to the ACRIM I irradiance scale. With these corrections a composite TSI is constructed for the period from 1978-1997. This time series is compared with a model that combines a magnetic brightness proxy with observed sunspot darkening and explains nearly 90% of the observed short and longterm variance. Possible, but still unverified degradation of the radiometers hampers conclusions about irradiance changes on decadal time scales and longer.

scholarly journals SOLAR ASTROMETRY: THE STATUS OF ART IN 2011

2013 ◽  
Vol 23 ◽  
pp. 443-450 ◽  
Author(s):  
COSTANTINO SIGISMONDI
Keyword(s):  
Solar Irradiance ◽  
Total Solar Irradiance ◽  
Evolutionary Stage ◽  
The Sun ◽  
Solar Diameter ◽  
The Status ◽  
Drift Scan ◽  
The Relationship ◽  
Climate Studies

Solar astrometry deals with the accurate measumerent of the solar diameter, and in general with the measurement of the shape of the Sun. During the last decades several techniques have been developed to monitor the radius and the irradiance of the Sun: meridian transits, telescopes in drift-scan mode, solar astrolabes, balloons, and satellites dedicated to the measurements of the solar diameter, and space measurements of the total solar irradiance are now performed to know the relationship radius-luminosity for the Sun in this evolutionary stage of its life. The feedback of solar astrometry in climate studies is of paramount importance. The status of art in the various fields of research here adressed is outlined.

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